OBSERVATIONS ON THE LIFE HISTORY OF TILLINA 



MAGNA 



' BY 



LOUISE HOYT GREGORY 



I Introduction 383 



n Material and methods , 3^5 



in Morphology and physiology 386 



IV Reproduction and encystment 39^ 



Introduction 



Formation of division cysts 



Formation of sporulation cysts 



Formation of permanent cvsts 



V Conjugation 399 



VI Observations on the life history 4°' 



The A culture 



The B culture 



1 Normal or control culture 



2 Stimulated cultures 



VII Regeneration and centrif uging - 41 ' 



VIII General considerations 41^ 



a Artificial rejuvenescence 4^2 



h Hertwig's "Kernplasma" theory 41S 



IX Summary 4^7 



I INTRODUCTION 



Tillina magna was first described in 1879 by Gruber, who found 

 the organism in great numbers in a fresh water culture which had 

 been sent from Vienna to Freiburg, and who regarded it as an 

 intermediate type between Colpoda and Paramecium. Kent, in 

 1880, placed it in the family Enchelinidae of the Holotrichous 

 ciliates because of its oral cilia, although he admitted that the 

 pharynx was strikingly like that of Conchopthirus. Biitschli, in 

 1888, mentioned Tillina magna merely as a synonym for Conchop- 



Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, in the 

 Faculty of Pure Science, Columbia University. 



The Journal of Experimental Zoology vol. vi, no. 3. 



